3D printing an entire car

Several months ago I instructed the internet to tell me about anything concerning 3D printing, but I usually now file the resulting emails under: to be looked at later if at all. People saying they have worked out how to make ever more intricate and ever more tasteless and 70s-ish napkin rings no longer excite me that much. Okay, I get it. The technique works. But come on. A napkin ring? That takes four hours to get made? (That’s how long the damn video goes on for! Although I now learn from another video at the same site that the process may have got stuck after an hour. So, how long does it actually take to 3D print this napkin ring? Don’t tell me. I really do not care.)

I earlier here pondered, and quickly discarded, the idea that 3D printing would be arriving in our homes some time quite soon. What 3D printing really is is better stuff-making, by the people who already make stuff.

So it was that this link – which does not concern brightly coloured napkin rings, but on the contrary is to a story (here is the original Wired version) about an enterprise that has used 3D printing to make the body of a car – really did get my attention. This car body is just as strong as a regular steel car body but much lighter, and hence much more fuel efficient. Oh sure, it’ll still be years before most cars are made this way, but this surely is the future starting to reveal itself, to those of us beyond the circle of specialists who are already paying close attention to such developments. As was noted in one of the comments on my earlier 3D printing here (that’s the link again), car makers (Mercedes was singled out for our attention) already use 3D printing, to make small but important car parts. So it won’t be a huge leap for them to use 3D printing to make rather bigger car parts, until hey presto, they’re 3D printing entire cars!

The comments on that earlier posting were very informative. But nobody, except me in the original posting, discussed the possibility that 3D printing could shift the balance of manufacturing power somewhat back from the getting-rich world to the already-rich world. This is an idea you now hear quite a lot. Thinking about that idea some more, I think that 3D printing may be less of a macro-economic game changer that at first it looked, to me, like being. The idea, in other words, resembles the idea of a 3D printer in every home. After all, here is yet another manufacturing method, devised and developed in the richest and cleverest places, but then, surely, easily unleashable in any place, and in particular in places that are merely getting richer and getting cleverer. Does that change the game? It sounds like the game as usual to me. Which could be why nobody else thought the idea worth commenting on. But maybe I am getting that wrong.

February 28th, 2013 |

30 comments to 3D printing an entire car

Why would you make a car body out of $5-a-pound plastic when you can make it out of $0.40-a-pound steel? And a 3D-printed car body will take a lot more processing to acheive a class A automotive finish than a steel body does. And it will degrade in use.

A $50,000 Morgan 3-wheeler? Even at the alleged weight reduction, you would have to drive it for eleventy-hundred years just to recover the cost in fuel savings.

Remember, I’m they only commenter here that uses SOTA 3D printing machines every day, IOW, actually knows what he’s talking about. This project is geek pr*n, bears no relationship to real-life manufacturing. And will not for many years to come.

I read articles like this and I just throw up my hands. Doesn’t anybody employ reporters with even a grain of common sense and basic math skills anymore?

You make a 3D printed part because the part is complex and would otherwise require complex and expensive tooling. You never intend to mass produce parts this way. Once you test your 3D part and convince yourself that it will work as predicted, then you buy the expensive tooling that allows you to make the things for $.05/each. Llamas is right, unless your demand is for one complex part only, it is not for production.

A key question would seem to be: Are there any useful things that can be made with 3D printing, which can’t be made without it? The above comments imply: no. Is that really the case? Maybe: Yes, for a whole range of extremely small things. No, for things now regularly manufactured. ???

If this actually produces similar structural characteristics at half the weight, I expect the auto-racing world to jump on it with both feet regardless of cost. Other than that, though, it’s a tech demo, not a real mass-production method. Now that said, with some early adopters jumping in, it’ll probably get more reasonable over time. But we’re a long way off yet.

“Are there any useful things that can be made with 3D printing, which can’t be made without it?” Well this car seems to have parts that are normally lots of parts connected together, but thanks to 3D printing are now one part, with various efficiencies that brings.

To further remedy the issues caused by modern car-construction techniques, Kor used the design freedom of 3-D printing to combine a typical car’s multitude of parts into simple unibody shapes. For example, when he prints the car’s dashboard, he’ll make it with the ducts already attached without the need for joints and connecting parts. What would be dozens of pieces of plastic and metal end up being one piece of 3-D printed plastic.

“The thesis we’re following is to take small parts from a big car and make them single large pieces,” Kor says. By using one piece instead of many, the car loses weight and gets reduced rolling resistance, and with fewer spaces between parts, the Urbee ends up being exceptionally aerodynamic.” How aerodynamic? The Urbee 2′s teardrop shape gives it just a 0.15 coefficient of drag.

“A key question would seem to be: Are there any useful things that can be made with 3D printing, which can’t be made without it? ‘

and a better question might end with the words ” . . . . which can’t be made ECONOMICALLY without it . . . ‘

and the answer is an unequivocal YES.

Two classes of stuff – I deal with both.

– one-off and prototype stuff, where you need to see if it will work and sell before you commit to tooling – or where you know you will never make another one just like it. Also useful for making stuff that is very hard to make by conventional means (lots of individual parts plus assembly) but very easy to make by 3D printing. For example, I make low-precision reduction gear trains by 3D printing – all-in-one, no loose parts, no assembly.

– specialized, short-run or limited-life stuff.

I have a perfect example of the second class on my desk right now. It’s a handle for an office machine that is experiencing a high failure rate in the field. There’s 1700 machines in service, but it’s out of production and the part that breaks is no longer serviced by the manufacturer. Monthly usage ~ 30 pieces, declining.

Cost for a new mold to make the part as-designed – $18,000. Part cost for the molded part – $3-$4 (due to high set-up and short-run charges).

In about 4 hours of my time (= $500) I designed a replacement part to be 3D printed. Because it doesn’t have to be molded, it can have thick, heavy sections and be generally bulletrpoof.

Cost of the 3D printed part – $18 each. Cost delta over molded part – $14. We’d have to make 1300 of them before the molded part became more cost-effective – that’s 43 months supply, and 75% of the entire installed base. This does not make sense to do.

For work like that, 3D printing is absolutely and highly effective, and cost-efficient. too

This technology also has interesting implications with respect to liberty. Defense Distributed recently printed a 30-round AR magazine and an AR lower receiver, and fired several hundred rounds through both. I’m sure that our politicians broke out in hives when they heard the news.

Great note, Brian, and an especially big thanks to llamas for what sounds like extremely reasonable current use & near future trends.

The out-of-production repair will be a gradually increasing niche market.
It will likely also be increasingly popular in out-of-the way locations, like Rwanda, where air-transport is a bit expensive for lots of spares.

I’d guess more manufacturers would be slowly beginning to make things so that their replacement/ repair parts could be printed. (I wonder what that will do for increasing or decreasing the standardization.)

3D printers are truly awe inspiring. They are a future that I hope I live to see. If you want to know how they are being used for more than napkin rings, then check out what Rolls-Royce are using them for. Like, the design of their engines.
And, guess where a large amount of the ingenuity of 3D printers comes from? Israel. Now, if there was ever a tangible demonstration of beneficial and malignant societies this is it. When did a muslim country ever produce anything that benefits mankind? Long live Israel, long live Western Civilisation.

Said this here before but it’s worth repeating. Those defdist guys are going up a blind alley. As Llamas says, there’s no sense printing stuff can be made by existing & more effective methods except in special cases. But, to quote Rumsfeld, it’s the unknown unknowns. There’s stuff going to possible to print can’t be made by any other method.
Returning to AR15 receivers. The AR15’s a product of a technology goes back to Italian bell-casters in the C13th. That’s the way design works. It builds on available materials & methods. The best way to make an AR15 is by those methods because it’s the child of those methods. You want to make a firearm with a 3D printer, start with the printer & a clear slate. Design to the printer’s advantages & limitations. What are they. Per Llamas above, for a start. Tooling & operator time are expensive. Once it’s written, software’s free. The AR15’s a design for passing cheap disposable rounds through an expensive to produce mechanism. A printed design, to do a similar task, would have entirely different constraints.

Remember the Intel 4004 processor and the Intel 1102A dynamic ram? (see http://content.scu.edu/cdm/singleitem/collection/svhocdm/id/660/rec/19 and http://www.cpu-zone.com/RAM_History.htm) That is where the whole 3D printing thing is right now. Now what could you do with a 4 bit computer and 1K of dynamic RAM? Why you could make nifty little controllers. And when you needed to build niftier ones, you were ready to by the 8008 CPU, then the 8080, the 8086, 286, 386, 486, 586… and memories that went up and up until today we carry 16GB sticks on a key chain. All in 40 years.

What is important about the 3D printing concept is that material objects have now been moved onto the same Moore’s Law curve as computing power.

Do NOT mistake today’s ‘4004’ 3D printer which makes napkin holders for tomorrow’s Core-i7 3D printer that can print you a new pet cat.

Dale Amon: “What is important about the 3D printing concept is that material objects have now been moved onto the same Moore’s Law curve as computing power.”

This seems to be the key point. If something like Moore’s Law does apply to 3D printing, then the important thing is to get some particular application working, however expensively, so that it can be sped up later. A 3D printed car now is insanely expensive and time-consuming to make thus. But when Moore’s law starts to do its thing …?

But does Moore’s Law apply? The difference would appear to be, as llamas said in the very first comment above, in the cost of the raw materials. These loom very large, and will surely continue to do so. 3D printing will presumably get much quicker. So, will the over-all costs nosedive the way computing costs have? Will 3D printing improve not only in speed and cleverness, but also, in particular, in its cleverness at using cheaper physical inputs? With tiny objects, input costs count for less. But for things like cars …?

It’s noticeable that (regular 2D printer) toner cartridges haven’t dropped in price nearly as much as printers or computers.

Brian. I think you’re still clinging to the wrong paradigm. Dale referenced that old 1K of dynamic RAM. The USB sticks I now carry are 64Gb. Two of them. Cost me £30 each. Probably more memory capacity than the entire United States had 40 years ago. And they’re full. If they’d had them 40 years ago what could they have put on them that you’d want to put in your pocket? The entire tax records since the civil war?
You talk about 2D printers to paper. But how many people print to paper? What? MP3s? The 2D printers a casualty not a success. The success was optical write to disc. Have you seen a disc drive that doesn’t, recently? Last I bought, to go with the netbook, is hardly bigger than the disc. Cost £20. They started in the thousands & were only bought by industry. And even that’s dead tech.
Llamas is right. There’s very little application for a 3D printer in the home. These printers to print what they can print. They’re toys. Like the old ZX Spectrum. You really don’t find uses for your laptop? Your phone?

I am not clinging to any wrong paradigm. I mention 2D printers because the cost of the physical inputs seems relevant to the cost of 3D printer physical inputs. 2D printer inputs have not fallen much in price, even as 2D printers have got dramatically cheaper. This would suggest that 3D printer input costs won’t fall that much either. But, maybe that’s wrong.

USB sticks now carry a lot of data and cost very little. etc. I know this. We all know this. That’s Moore’s Law in action. What I am asking is if Moore’s Law applies, as Dale Amon asserts, to 3D printers, the way it clearly does to USB sticks and the like. And I would truly like to know. I suspect Dale Amon is being somewhat optimistic. Insofar as the current limitations of 3D printing are in computer power and hardware cleverness, yes, increased computer power will improve 3D printing dramatically . But if physical input costs remain approximately where they are now, Moore’s Law will not apply.

There are three physical/kinematic limits to the speed of 3D printing.

The first has to do with the speeds with which you can transit the print head in X and Y

(note that ‘print head’ is merely used as a generic marker for ‘fused deposition device’)

while still supplying feedstock at the required rates.

I do not think this has any limits that would be of concern. How fast you accelerate something is merely a function of how much force you are prepared to apply.

The second concerns the chemistry of the support material. Many people don’t understand that 3D printers almost always print 2 materials – the material of the part being built, and then a disposable support material, which is like scaffolding for the part under construction. The support material is removed when the part build is complete, either mechanically or (most-often) chemically, by dissolving it in a chemical bath. This is a major factor in the speed of delivery of the finished part – how long it takes to wash out the support material. A lot of the clever, patented technology in this area deals with minimizing the mass of the support material and making it wash away as quickly as possible.

Again, this is merely a problem of chemistry. The process is generally slow because the chemicals used tend to be quite benign. If you want the support gone in minutes, that would be easy to do, although perhaps rather more complex than an open bath of water-soluble chemicals. I believe there are systems available which reduce wash time from ‘a few hours’ to ‘many minutes’.

The third limit is a thermal limit. This is the big hurdle.

Fused-deposition is a delicate balance of temperatures – the feedstock is delivered in a continuous stream of liquid material, which has to fuse almost-instantly with previously-deposited materials. It must be hot enough to stay liquid as it exits the deposition device, but not so hot as to overmelt the previously-deposited material. The already-built material must be hot enough to allow the deposited material to fuse with it, but also cold enough to provide support and not slump or re-melt. This means that there is a zone of remelt bettween the new material and the old which is only 2 or 3 thousandths of an inch deep, being consistently maintained while the print head travels at speeds of 20-30 inches per second.

It’s like arc welding – there is a limit to the speed with which you can lay down weld metal that is defined by the rate at which you can selectively-remelt the base material. The required temperature gradient has a third variable – time – which is very-narrowly delimited by the melt temperature of the material and its thermal conductivity.

That’s where the problem lies.

Moore’s Law appears to apply relatively accurately to computing power because at the time it was postulated, memory and processor technologies were incredibly-coarse when measured with a molecular yardstick. But as devices approach the molecular level (within a few orders of magnitude), the rate of change will inevitably slow and diverge more and more from the Moore’s Law prediction.

The functionality of FDM technques is already at a pretty-fine level – a good balance has been found between granularity of build quality and speed that stays in the possible thermal regimes of the materials in question. To deposit material faster, you must deposit it in a coarser stream (sacrificing accuracy of the part) – the thermal parameters will not be denied. So a Moore’s Law-type progression will not apply unless/until materials can be discovered which have lower melting points and lower thermal conductivity and yet are still acceptable for finished models.

The future of rapid-prototyping methods may lie with processes which do not have thermal limitations. There are some very-interesting possibilities in laser-cut-and-fused laminar manufacturing techniques, which do not rely on melting feedstock and then fusing it together. But these techniques have limitations on size and fine detail. They work wonderfully for cylinder heads and turret-press frames, not so much for gear-trains and jet engine impellers.

Pardon my ignnerance – how do I post a photograph here? That doesn’t involve me posting it to some other website first?

Brian, I’m trying to look at it in the same way as the development of computers. If you start at maybe the 4004 systems that Dale mentioned, the point where they stop being rooms of equipment & are possible to pick up what does the future look like? You have a machine that’ll crunch numbers. What’s the potential? Maybe you can see them becoming faster & more capable & cheaper but there’s only so many numbers need crunching. Can you see the techies playing the first game of paddle tennis, communications moving from university notice boards to ubiquitous e-mail, cell phones, downloading media…. All of that starts with a bit of silicon on a chip.
I haven’t a clue where 3D printing heads to. It’s a simple ability. To create an artifact out of data. Like number crunching. I’ve had some experience of doing the same thing subtractively. A CNC machine’s a joy to watch, cutting complex shapes out of anything can be cut. I’ve even had experience of making car bodies out of composites. If we’d have been on billed time making the moulds, laying up mat & resin, hacking the designing & building of a complete rolling shell. $50K & 2500 hours wouldn’t have covered it. Didn’t look nearly as neat as that baby. If I was given a 3D printer tomorrow, haven’t the vaguest what I’d do with it. But I think it’d probably come up with some suggestions.

Llamas. You’ve described the technology’s limitations. What are it’s strengths? For instance, what’s the potential for depositing remeltable materials at low(?) temperatures? One of the acquired skills was some years learning to be a goldsmith. I seriously know about working to exacting standards. What’s the potential for fabricating an equivalent to wax models for casting moulds? The idea of going straight from design to metal, by automating the intervening steps, intrigues. Gold’s cheap shit. It’s the work that costs.

Incidentally, it’s what pisses about the guys trying to make plastic firearms. They’re so hypnotized by their 3D printers they don’t see them as just another tool. Make the part in plastic, the moulds in whatever, the AR 15 bits in bronze. It’s…well…bronze age tech. Lost wax casting. Except without the wax. Back garden stuff.

What are the limits on the material that can be used. I would assume, possibly wrongly, that there is a relatively limited range of organic based plastics that can be used because they have the right mix of properties. Is this limited selection of materials a restriction on what can be achieved ?

And thanks to Llamas for a genuinely informative series of posts, so helpful when one has an actual practitioner to comment.

I think that over the long term, printing an AR-15 lower the way it’s done now is *necessarily* a transitional process. The few people I know who are doing this is not because they need an AR-15 lower – the reason is ‘because I can’ – it’s as a political statement. As of today, anyone who wants to be a firearm owner under the radar will have obtained a number of “80% lowers” and will be hard at work with a bench drill, but the very act of fabricating something that The State considers dangerous – however flimsy – out of a bag full of plastic stock is a subversive act.

Sure, at the moment, it’s “Cargo Cult Manufacturing”, but the patterns for those lowers is already different from the engineering design that was released a few weeks ago.

The fanbicators have modified their designs to deal with stress points where the falures were, and they turned around many iterations of a design in less time than it would take a cast-maker to set a new mold.

It wouldn’t surprise me to see by this time next year, a functional lower that was component-compatible with a traditional lower, with maybe laminated metal reinforcement and a profile noticeably different from current designs – I’ll defer to the people who actually do 3D fabrication on that point – but the issue is that not just designs, but techniques are going to evolve very quickly.

And I’ll bet money that casting will become a cottage industry. I can’t think of a *better* way of making molds than with a thermoplastic, that can be formed by a computer that can calculate casting shrinkage along with optimal locations for spigots and vents. I wouldn’t want to fire a lower cast from pot metal, but I’d expect more variety in the casting materials than just bronze.

I wonder which laws would apply here? If you wanted to build a car with your own printer, maybe Jaguar would let you download the instructions into your home computer for a ‘reasonable’ price, once they’ve shown off the latest jag at a car show. So this would be covered by copyright laws. We should sort these issues out now, before we’re suddenly confronted with the future gizmoes today.

“What are the limits on the material that can be used. I would assume, possibly wrongly, that there is a relatively limited range of organic based plastics that can be used because they have the right mix of properties. Is this limited selection of materials a restriction on what can be achieved ?”

and that’s it in a nutshell.

You can go to the corners of the physical/thermal envelope, but you always have to give up something.

Bloke in Spain spoke (for example) about the possibility of making patterns for investment casting. This has been done semi-successfully, but the problems of making and controlling a feedstock that’s suitable for the process have not really been overcome. This material would be more like a wax than a plastic, hard to make into a consistent filament or powder feedstock.

Better results have been obtained by using 3D printing to make the molds for casting investment-cast cores, but the (relatively)-poor surface finish limits design and does not allow for near-net casting, which is one of the goals of modern investment casting in the first place.

And so it goes.

I’ve had a fair amount of sucess usuing the process to make tooling for processes like drape-molding and vacuum-forming, and I don’t see why it wouldn’t work for blow-molding and similar processes although I’ve never heard of it being done.

And so on. If you want the process tuned to some corner of the material envelope, you have to give up something else. The makers have already produced a process which is pretty-optimal for most applications.

I think you have to see the process for what it is. As Bloke in Spain describes, people like Distributed Defense and these car-making guys are just hypnotized by the process, and thye are applying it to everything whether it makes sense or not. Making the heating ducts of your car out of $5/cubic inch plastic by a process that takes 10 days on a $40,000 machine, instead of using 9¢-a-foot flexible hose, definitely falls into the category of ‘because I can’ and not ‘because it makes any sense’. All this talk about all-in-one manufacturing being more-compact and lighter, and therefore ‘better’, is mostly hype and/or self-delusion, because it ignores the real world that the product is supposed to be aimed at. Something built like this rapidly becomes impossible to assemble, finish, service or repair.

IBM once famously-designed the chassis of a business machine using this principle – a single weldment made out of fully-tooled sheet metal parts. It all tabbed together like a jigsaw puzzle and was robotically-welded together. It was incredibly strong, incredibly light and very cost-effective. Boothroyd/Dewhurst run amok. This was in the early days of CAD, and everything was still 2D. But the design absolutely worked and fit together – on the screen.

But it was impossible to assemble in any realistic way. At one point, they were assembling drive belts to the chassis before welding it together, and wiring a spare belt in place for future repairs. And the service costs were completely out of control – you couldn’t get to anything to fix it. Service techs were cutting access holes in the chassis. It was a complete fiasco.

This approach works well for a product that is essentially-disposable. The printer engine at the heart of many HP printers is made this way – it can only really be assembled, it can’t be disassembled, and it certainly can’t be repaired beyond some very simple attentions. Maybe not the best approach for a costly product like an automobile that’s filled with failure items.

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